This invention relates to a cover for a reservoir of a master cylinder.
Covers for reservoirs that hold a reserve quantity of brake fluid for a master cylinder have been attached to housings in a variety of ways.
Initially all covers were filler caps that were attached to a housing by threaded connections such as disclosed in U.S. Pat. No. 3,068,651. Unfortunately, the threads could be damaged by an operator on replacing the cap after checking the level of brake fluid. Unless the cap is completely tight against the housing, a leak path to the surrounding environment for brake fluid can occur. Thereafter, it was decided that an effort should be made to reduce the possibility of damaging the sealing components of the cover. It was suggested that the cover could be made of a plastic member which snapped onto the housing of the master cylinder reservoir, such as disclosed in U.S. Pat. No. 3,077,283. This type of cover was more economical to produce, however, because of the coefficient of expansion for the metal master cylinder reservoir housing and the plastic cover during extreme temperature, it was possible under some conditions to create sufficient pressure in the reservoir to blow the plastic cover off the metal housing. Thus, it became apparent that a lock such as disclosed in U.S. Pat. No. 3,317,079 was necessary to assure that the reservoir was sealed from the environment under all operating conditions. Unfortunately, because of space problems such locking structure cannot be used on all vehicles. Thus, covers were again attached to the reservoir housings through bolts such as disclosed in U.S. Pat. No. 3,344,944. This type of attachment is completely adequate, however, a similar method of attachment was desired and as a result, the bail wire structure such as disclosed in U.S. Pat. No. 3,494,131 was developed. The bail wire type attachment structure is currently used on the majority of master cylinders used on vehicles manufactured in the United States.